Low-Frequency Negative Permittivity Behavior in Carbon/Cement Composites With Superior Formability

Abstract Composites composed of Carbon Black (CB) and cement, which exhibit negative permittivity, have attracted significant attention owing to their unique characteristics and extensive application potential. In this study, CB/cement composites were fabricated using cement as the matrix material and CB as the functional filler. The electrical conductivity, impedance characteristics, and permittivity of composites were systematically investigated and analyzed. The results demonstrate that the electrical properties of the composites are influenced by their compositions and microstructures. As the CB content increases, a conductive network gradually forms, altering the conduction mechanism and leading to percolation behavior. Once the CB content exceeds the percolation threshold, plasma-type negative permittivity dielectrics emerge. Both the modulus of the negative permittivity response and the plasma oscillation frequency increase with higher CB content, which is consistent with the Drude model. This study successfully prepared easily formable CB/cement composites with tunable negative permittivity, marking a significant advancement for the future development of electromagnetic wave absorption and shielding.